Tom Coughlin has faced giant challenges in the NFL, from somehow taking a Jaguars expansion team to a pair of AFC Championship Games, to developing Eli Manning, to winning two Super Bowl championships with upsets over Bill Belichick and Tom Brady, to training camp 2014, which officially broke up Thursday night.

And with the regular season nearly three weeks away, Coughlin’s latest giant challenge is shaping up ominously as his greatest — with a remodeled team that looks as if it could use a second training camp.

Humpty Dumpty had a great fall last season, prompting GM Jerry Reese to go on a drunken-sailor free-agent binge, and it is Coughlin’s job to take all the new pieces and put Humpty Dumpty back together again and get the Giants back to the playoffs. Just because the faces have changed hardly means the great expectations have changed: John Mara demands a team that will again make opponents nervous instead of a team that makes him nervous when he watches it.

The new offense undoubtedly is making him nervous, even if Victor Cruz hasn’t been targeted in the two preseason games, even if No.1 draft pick Odell Beckham Jr. and left tackle Will Beatty have yet to play, even if you dare not show your hand in preseason. “We want to be able to show what this offense can do,” Cruz said.

But it isn’t only teaching an old dog like Manning new tricks and a new system under a new offensive coordinator that demands Coughlin prove one last time that he is a great coach, a Hall of Fame coach, with the kind of Super coaching job he watched Bill Parcells do up close and personal at the end of the 1990 season with Jeff Hostetler as his quarterback instead of the injured Phil Simms.

It is molding a team in his image, fostering a chemistry and cohesiveness among an unusually large nucleus of significant players schooled away from the Giant Way.

It is getting Manning to stop throwing interceptions trying to do too much and being more discreet and more elite again.

Eli ManningPhoto: Charles Wenzelberg

The party line, from Coughlin and from Manning, is the changes have re-energized them. But never before has Coughlin been asked to integrate as many as a dozen free agents, while counting on as many as four second-year players (Justin Pugh, Johnathan Hankins, Damontre Moore, Cooper Taylor) and as many as five rookies (Beckham, Weston Richburg, Jay Bromley, Andre Williams, Devon Kennard) to make an impact.

Then there is the matter of reaching a philosophical consensus on this hybrid West Coast offense with rookie offensive coordinator Ben McAdoo while guiding him through the New York minefield that can rattle wide-eyed, first-time playcallers.

“It’s obviously a challenge,” Cruz told The Post, “but I think he’s up to it. I think he’s done a great job so far bringing everybody together. It’s funny, there’s a lot of new faces, but we’re still a family. Everybody’s hanging out with everybody, nobody’s separate, everybody’s on the same page. He’s done a good job of keeping everybody close, and I think training camp had brought us closer as well.”

So it is Coughlin who stands atop The Post’s list of Six Men Who Must Be Giants:

Eli Manning: He’ll be over 60 percent, but that 70 percent completion percentage goal is more a pipe dream. Manning, who has yet to complete a pass longer than 10 yards this summer, will take a shot Saturday night against the Colts — if only because muscle memory is due to kick in at some point — and welcome Cruz to the new offense. Running back Rashad Jennings will be a godsend as a receiver out of the backfield, and he and rookie Williams should give Manning a bullish ground attack and balance. But tight end, until further notice, remains as barren for Manning as cornerback is for Rex Ryan. Manning will get the ball out of his hand quicker — and he very well may have to once again unless and until the offensive line gels. “I’m not worried about the offense, they’re gonna get everything situated,” cornerback Walter Thurmond III said. “To be able to help them out, we have to play great defense. We’re just as big a part of helping their development as they are of helping their own development.”

Antrel Rolle peers in at Eli Manning.Photo: Charles Wenzelberg

Will Beatty: The offensive line, so offensive last season, is younger and deeper, but Coughlin desperately needs Beatty to put his broken leg behind him and be a reliable blind-side protector again. “I really didn’t have time to wallow in pity or sorrow,” Beatty said. The quarterback making quicker decisions off three-and five-step drops should lessen the stress on the left tackle, who makes his preseason debut in Indianapolis. “Yes, I have something to prove, but we all have something to prove. … I don’t think the weight on my shoulders is bigger than anyone else’s,” Beatty said. Oh but it is. His backup, Charles Brown, hasn’t exactly inspired comparisons to Rosey Brown. “I’m not dunking like I used to,” Beatty joked. “It’s not a one-legged hop by any means when I’m out there. I can do it all.”

Jon BeasonPhoto: Joseph E. Amaturo

Jason Pierre-Paul: There is no reason why JPP should not register double-digit sacks given an extra split second by the dramatically upgraded secondary. He’s healthy for the first time since his Monster of the Meadowlands sophomore season. Contract year. Time to get the quarterback. “He has that potential to be an elite pass rusher, and I think this is gonna be his coming-out year again,” Thurmond said, “especially with the secondary in the back end being able to have some tight coverage on receivers to where it gives those pass rushers ability to go out there and get after the quarterback, pin their ears back. That was the same situation that we had in Seattle.”

Antrel Rolle: The unquestioned leader of Big Blue now that Justin Tuck is in Oakland. “Just his playmaking ability, just the way he carries himself in the workplace on and off the field, just a really stand-up guy,” Thurmond said. “He really cares about his teammates, he cares about his brothers, and people feed off that.”

Jon Beason: The swaggerlicious quarterback of the defense when healthy. He’s recovering from a foot injury, and may miss the regular-season opener in Detroit.

The Eagles, in their second year under Chip Kelly, are The Team to Beat in the NFC East. For the Giants, it will take the very best of Tom Terrific, maybe a career year in a Hall of Fame career, to beat them.

This Team will be much improved over last season. O Line is better. Running backs are better, receivers are better, linebackers and Defensive backs are better, looking for Da Montre Moore and JPP to make noise from the Defensive End position this year. I honestly think Eli has to put up or shut up, he cannot lead the league in picks again this season. He is either boiling hot or freezing cold all the time now and more often than not, he is cold.

My take is that the unquestioned leader of Big Blue is Eli Manning. His character, behavior, and presence moves through the entire locker room. Other leaders branch off from his unique presence. Quiet guy. Big presence. Tuck sulked way too much. Antrel Rolle is a great positive leader. A terrific complement to Eli's calm and positive leadership.